BACKGROUND: Following the ban on the use of growth stimulant antibiotics in many countries, interest has arisen in finding a suitable alternative for antibiotics in poultry production. OBJECTIVES: The aim of this study was to investigate the effect of supplementation of two levels of nano-copper (0 and 100 mg/kg) and two levels of mannan oligosaccharide (0 or 1 g/kg) as natural growth stimulants on digestibility of nutrients and performance in broiler chicks. METHODS: At the end of the second week of breeding, 160 Cobb-500 broiler chicks were assigned in four treatment groups. For each treatment, four replicates (10 chicks per replicate) were considered. Experiment was conducted as a 2×2 factorial model in a completely randomized design. Results: No significant differences in digestibility of nutrients and growth performance between birds that ate the supplements with control group were observed (p>0.05). CONCLUSIONS: Mannan oligosaccharides and nano-copper on growth performance and nutrient digestibility in broiler chicks had no significant effect. At the doses used, concomitant supplementation of copper and mannan oligosaccharide did not have a positive effect on traits that were studied in broilers.